ULTRAMARINE BLUE OR ULTRAMARINE AZURE

There is some evidence that a blue was extracted from Lapis Lazuli found in Persia in early times; used in Europe long before any of the recipes for extracting it were written, and that the name ultramarine refers to the color and not the actual stone. It was therefore an adjective which was applied to other important commodities as well. It served to distinguish the genuine lapis lazuli ultramarine from other tube pigments, in particular the blue copper mineral pigment, azurite. As a pigment name, it has been traced to Italy at the beginning of the fourteenth century. Archeological evidence and accounts by Pliny and Theophrastus show that lapis lazuli was used as a semi-precious stone and decorative building stone from early Egyptian times. There is no evidence that it was used as a pigment by them or the Greeks and Romans, all of whom had a very satisfactory blue in the synthetic copper silicate pigment Egyptian blue, of which the secret of manufacture has been lost.

The earliest occurrence was in the sixth and seventh century wall paintings in cave temples at Bamiyan in Afghanistan. It has been identified to Persian miniatures of the thirteenth and fourteenth centuries; on Chinese paintings of the tenth to eleventh centuries, and Indian mural paintings of the eleventh, twelfth and seventeenth centuries. When it was used in Italy, its most extensive use was in illuminated manuscripts and panel paintings, complementing the use of vermilion and gold, and was as expensive as gold to work in. Many contracts for paintings specified the use of ultramarine, and the patron would have to agree to buy it, just as he would for the addition of gold leaf. The highest quality and most intensely blue-colored ultramarine was often reserved for the robes of Christ and the Virgin. The size of the picture and the status of both artists and commission seem also likely to have influenced the use. Azurite was often used as the underpainting tone as it was more economical, though other traditional blue tones would have been used as well. (It is important to note, that the use of such expensive paints would add as much status to the piece as the piece itself, and that as the bourgeoisie middle class became more and more important in time, it was a bit like the modern nouveau riche purchasing the objects of status from Chanel and BMW; these things became important as markers in themselves).

Chemically, the mineral lapis lazuli from which the pigment is made, is an extremely hard and complex rock mixture: a mineralized limestone containing grains of the blue cubic mineral called lazurite, which is the essential constituent of the pigment. Also present however are two isomorphous minerals, one containing sulphate and the other, chloride, both of which sometimes occur in a blue form, as well as other colors. There are other silicates which may also be present, creating variables in the quality and appearance of the stone. The best are of a uniform deep blue, but can be paler as there is a great deal of white calcite and iron pyrites in it that sparkle like gold; there is also the possible intermingling with white crystalline materials. As it is such a hard stone, it is difficult to separate the pigment from the other constituents. The aforementioned mining quarries of Badakshan (now in Afghanistan) were described by Marco Polo in conjunction with a journey he made in 1271, where he specifically states that the mineral was used for the extraction of blue pigment. These quarries supposedly provided almost all the lapis lazuli to Europe. IN the mid 1800s they were somewhat out of use, but as of the 1960s, mining had been resumed. It was most likely imported into Europe via Venice, the principal port for trade with the east, thus it was referred to in texts as coming from "across the seas".

There were however other blues that were imported this way that are now obsolete and we have very little information on, such as Yemen alum or Armenian Bole. Nicholas Hilliard, the sixteenth century miniaturist remarked that the darkest and highest ultramarine blue was the ultramarine of Venice and that its prohibitive price compelled painters to use other blues such as smalt and blue bice (artificial azurite). Lapis lazuli is a somewhat rare material, and the only other sizable deposits are near lake Baikal in Siberia and in the Chilean Andes, neither of which was mined until the nineteenth century. There are smaller deposits in Argentina, Burma, Canada and the USA. There are nineteenth century accounts which speak of deposits in Italy, but of insufficient quantity or quality to have been useful in providing a supply of pigment. The blue cannot be separated from the impurities by washing with water, as noted in Byzantine texts, as doing so would create a gray powder. By the twelfth century they began to invent more complicated measures of extraction, but there is no evidence as to what these early recipes were. The Arabian alchemist Geber in the thirteenth century mixed the powdered lapis with powdered resin and then washed it with water. There was also a practice in fourteenth century Italy which may have been a product of Moorish ingenuity, which consists of mixing the powdered lapis with a paste of wax, oil and resin, and kneading the mixture under water or lye until the blue came out in the water, largely free of the uncolored parts of the mineral.

The fullest account was Cennino's, written at the close of the fourteenth century: CENNINO: "To begin with, get some lapis lazuli... pound it in a bronze mortar covered up so that it may not go off in dust; then put it on your porphyry slab and work it up without water. Then take a covered sieve such as the druggists use for sifting drugs, and sift it, and pound it over again as you find necessary. And bear in mind that the more finely you work it up, the finer the blue will come out, but not so beautifully violet in color... When you have got this powder all ready, get six ounces of pine turpentine from the druggists, three ounces of mastic and three ounces of new wax, for each pound (i.e. 12 ounces) of lapis lazuli. Put all these things into a new pipkin, and melt them up together. Then take a white linen cloth, and strain these things into a glazed basin. Then take a pound of this lapis lazuli powder, and mix it all up thoroughly and make a plastic of it, all incorporated together. And have some linseed oil and always keep your hands well greased with this oil, so as to be able to handle the plastic... When you want to extract the blue from it, adopt this method. Make two sticks... and then have your plastic in the glazed basin in which you have been keeping it, and put into it about a porringerful of lye fairly warm; and with these two sticks, one in each hand, turn over and squeeze and knead this plastic, this way and that... When you have done this until you see that the lye is saturated with blue, draw it off into a glazed porringer. Then take as much lye again and put it on the plastic... and go on doing this for several days in the same way, until the plastic will no longer color the lye, and then throw it away, for it is no longer any good... If you have eighteen porringers full of the yields, and you wish to make three grades of blue, you take six of the porringers and mix them together and reduce it to one porringer; and that will be one grade, and in the same way with the others. But bear in mind that if you have good lapis lazuli, the blue from the first two yields will be worth eight ducats an ounce. The last two yields are worse than ashes; therefore be prudent in your observation, not to spoil the fine blues for the poor ones... and keep this to yourself: for it is an unusual ability to know how to make it properly. k Know, too, that making it is an occupation for pretty girls rather than for men; for they are always at home, and reliable, and they have more dainty hands. Just beware of old women."

As it was expensive enough to have become an instrument of luxury, Cennino's advice was to exhibit this color in conjunction with metallic gold, thus reaching the peak of highest elegance and intrinsic worth. This intrinsic worth has gone out of painting now entirely. But in the middle ages they lavished costly materials and unlimited service upon their churches; and in the Renaissance, the society of Europe looked kindly upon the exaltation of wealthy individuals, the function of art therefore to provide the marks of individual distinction. Slowly, the ruling classes began to use the artists to point the distinction that their wealth and power made between them and their fellows, thus paying hefty fees for blues and golds. In manuals of painting of all periods, there are warnings against counterfeited and adulterated natural ultramarine, its costliness making it an obvious subject for such practices. Very few could detect flaws in gems, or even know real from the false. Therefore, in market or from dealers, often the powder would be cut with whites which were undetectable at first, or the gems themselves would be small veins of blue rather than saturated areas.

Over time, these additives have shown up on the work, as veins of white around the edges of cracks, and in many other forms. The natural ultramarine however, has a high stability to light as is proven by the fact that examples on paintings as much as five hundred years old have as intense and pure a blue color as either the freshly extracted pigment or the best synthetic. j Even heating to redness has no visible effect, and early in the history of the pigment this was the only way to truly distinguish the general article from other substances or adulterations. There is a disorder known as "ultramarine sickness" which has occasionally been noted on paintings as a grayish or yellowish gray mottled discoloration of the paint surface which also occurs from time to time with artificial ultramarine used industrially, which is brought about by the action of atmospheric sulphur dioxide and moisture. An alternative cause may be the acidity of an oil or oleo-resinous paint medium: the slow drying of the oil during which time water may have been absorbed to cause swelling, opacity of the medium and therefore whitening of the paint film. As it has also occurred when mixed with smalt, this sickness cannot be assigned to a single cause. Also, artificial ultramarines have been known to fade when in contact with lime; for instance if it is used took color concrete or plaster. This has lead us to speculate that possible fading of the natural mineral pigment may possibly be the result of its contact with the lime plaster of fresco paintings.

On Dutch pictures of the seventeenth century, ultramarine natural was used over a white ground as a local color for air and draperies; done in tempera no doubt, as Van Dyck did this as well. A difference in color tone and value was achieved by glazing with other colors, such as ochre and white, particularly in skies, over the ultramarine. This was made necessary by the cost of the pigment, which would be largely lost in mixtures. The graduations were easily achieved and quite beautiful, but the cost eventually drove it into obsoletion with the invention of artificial ultramarine. Ultramarine is imitated nowadays by a process which was invented in France in the eighteenth century as a result of a prize offered by the French government. The raw materials of ultramarine manufacture are soda and china clay and coal and sulphur, all common and inexpensive materials. The process requires skill, is inexpensive, and the product is many thousand times less costly than genuine ultramarine prepared from lapis lazuli. It is known as French ultramarine, French blue, Guimet's blue, permanent blue and synthetic ultramarine.

The first observance of the substance was made by Goethe in 1787, when he noticed blue deposits on the walls of lime kilns near Palermo. He mentioned that the glassy blue masses were cut and used locally as a substitute for lapis in decorative work. He didn't mention whether the idea had arisen of grinding the material for use as a pigment. Tassaert, who found the blue masses in soda kilns of the glass factory at Saint Gobin in France, submitted samples for analysis in 1814 to Vauquelin, and to the French Government on the basis that a method for synthesizing ultramarine might be investigated. IN 1824 when the Societe offered a prize of 6,000 francs for this discovery, whereby it would be manufactured at a cost of not more than 300 francs per kilogram, there were many submitted imitations based on cobalt or Prussian blues, with no regard to the analyses of natural ultramarine. 4 years later it was awarded to Jean Baptiste Guimet, and hotly contested by Tassaert for many years. Guimet's right to the prize was upheld in France, and he started a factory for the commercial production of the pigment in 1830. Chemically the artificial ultramarines are not distinguishable from the blue particles of genuine lapis; you can only tell by the percentage of colorless optically active crystals, whereas the artificial is pre blue and free from diluting elements. If the two are mixed, the results cannot be distinguished with certainly from finely ground genuine ultramarine of good quality. The importance of the intrinsic value of this pigment in medieval painting has little to do with its appearance; but a great deal to do with an understanding of the Middle Ages and their osmosis into the renaissance. Ultramarine was in some ways less important to Medieval painting than azurite, as it did not become common until the fourteenth century, and was less used in he middle ages than has been supposed. It was attached more to the centers of wealth and luxury, but fifteenth century German texts seldom know it except by name, and mention very inadequate substitutes for the fine azure as they make it across the sea." IN 1549, Valentin Boltz said that "Ultramarine is prized as the choicest of all, but in German lands is seen seldom and in small quantity". In fifteenth century Italy it was the standard of quality (all French recipes being of Italian descent, it was a choice somewhat there as well).

The popularity of this blue in early renaissance Italy and its comparative rarity elsewhere are probably due to the higher development of that personal luxury of which it was in Italy so often the obvious material expression in painting. Rich wares go to rich markets. We should also note, that artificial ultramarine became a common component of the impressionist and post impressionist palette, as opposed to natural ultramarine. And that even though Turner has been attributed as the first painter to popularize its use, that chemical testing has shown use of other colors which were thought to be ultramarine, and therefore this is now in question. Also, catalogues of color merchants from the 1850s lest several shades of artificial ultramarine blue, but none list the green, red or violet varieties, although they are still available as industrial pigments. Apart from the disadvantage of their rather low tinting strength, the lack of popularity of these other ultramarines as artists' pigments may be because, whereas there is absolutely no substitute for the distinctive hue of blue ultramarine, there were available to the artist by the second half of the nineteenth century excellent pigments such as cobalt green, violets, and chromium oxide greens. Cennino, late fourteenth century: "Ultramarine blue is a noble, beautiful color, perfect beyond any other; one could not say anything about it, or do anything with it, that its quality would not still surpass. And, because of its excellence, I want to discuss it at length, and to show you in detail how it is made. And pay close attention to this, for you will gain great honor and profit from it. And let some of that color, combined with gold, which will grace any work of our art, whether on wall or on panel, shine forth in every picture."

URANIUM YELLOW

Or Uranium oxide, light and dark, is regarded as a fast color in mineral painting [stereochromy], but is otherwise used only for china painting.